1. Field of the Invention
The present invention relates to a method, system, and program for providing an address format compatible with different addressing formats used for addressing different sized address spaces.
2. Description of the Related Art
In certain computing environments, multiple host systems may communicate with multiple control units (CUs) (also known as storage controllers, storage subsystems, enterprise storage servers, etc.) providing access to storage devices, such as interconnected hard disk drives through one or more logical paths. The interconnected drives may be configured as a Direct Access Storage Device (DASD), Redundant Array of Independent Disks (RAID), Just a Bunch of Disks (JBOD), etc. The control unit may configure one or more logical subsystems (LSSs), where each LSS is configured to include multiple volumes.
The host systems include operating systems, middleware (such as data bases) and applications that translate data requests from applications into an address that may be presented to the control unit. The control unit translates the received address into a physical location on a storage device from which to access the requested data. For instance, in certain environments, the host operating system presents an address having a cylinder number, track number, and record number in a specific format.
If larger storage volumes are added, the addressing format used by the operating system may have to be changed to add bytes to provide addressing for a larger storage space. If the addressing format is changed, then the data used by the current applications and operating system is migrated to the new storage system configured to use the larger addressing space and the applications must be migrated over to use the newer versions of the operating system that are coded to use the new address format providing access to the larger storage spaces. These migration operations can take a significant amount of time and be disruptive to the operating environment.
For these reasons, there is a need in the art for improved techniques for making larger storage spaces available to a current operating environment.